One of those serine proteases, thrombin, is the key enzyme for coagulation and plays a central role in venous and arterial thrombosis pathology in view, in particular, of its marked ability to cause autoamplification of the coagulation cascade (F. Toti et al, Sang, Thrombose, Vaisseaux 1992, 4, 483-494 and T. M. Reilly et al., Blood Coagulation and Fibrinolysis 1992, 3, 513-517).
The specific and direct inhibition of thrombin is more efficient and presents fewer risks of haemorrhage than treatment with heparin. Direct inhibitors of thrombin do currently exist, but the drawback of such peptide substances is that they are not active when administered by the oral route.